The Role of Hydrogen Bonds in the Stabilization of Silver-Mediated Cytosine Tetramers

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• 作者：Leonardo Andr茅s Espinosa Leal ; Alexander Karpenko ; Steven Swasey ; Elisabeth G. Gwinn ; Victor Rojas-Cervellera ; Carme Rovira ; Olga Lopez-Acevedo
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2015
• 出版时间：October 15, 2015
• 年：2015
• 卷：6
• 期：20
• 页码：4061-4066
• 全文大小：365K
• ISSN：1948-7185

文摘

DNA oligomers can form silver-mediated duplexes, stable in gas phase and solution, with potential for novel biomedical and technological applications. The nucleobase-metal bond primarily drives duplex formation, but hydrogen (H鈭? bonds may also be important for structure selection and stability. To elucidate the role of H-bonding, we conducted theoretical and experimental studies of a duplex formed by silver-mediated cytosine homopobase DNA strands, two bases long. This silver-mediated cytosine tetramer is small enough to permit accurate, realistic modeling by DFT-based quantum mechanics/molecular mechanics methods. In gas phase, our calculations found two energetically favorable configurations distinguished by H-bonding, one with a novel interplane H-bond, and the other with planar H-bonding of silver-bridged bases. Adding solvent favored silver-mediated tetramers with interplane H-bonding. Overall agreement of electronic circular dichroism spectra for the final calculated structure and experiment validates these findings. Our results can guide use of these stabilization mechanisms for devising novel metal-mediated DNA structures.